You Can't Teach an Old Time Lord New Tricks
by Settiai
Summary: The Fourth Doctor left UNIT without a scientific advisor when he went to travel the universe with Sarah Jane Smith. The Tenth Doctor decides to pick up where he left off.


The Doctor dove into the TARDIS, crashing into the control console in his hurry to grab the lever that would close the doors behind him. "Close faster," he muttered as a roar filled the room, loud enough to make him worry about possible deafness. "Faster, faster, faster!"

He glanced behind him, catching a glimpse of a giant mouth filled with extremely pointed teeth just as the doors finally whirred shut. Letting out a relieved sigh, the Doctor sank down to the floor with his back leaning against the console. "That's the last time I visit the Cretaceous Period, Arcateenian distress signal or not."

There was no reply. He wasn't certain whether to be disappointed or relieved.

After a few seconds, the Doctor pushed himself to his feet. He stood in front of the console for a moment, seemingly lost in thought, before grinning. "What do you say we stop at Betelgeuse Seven?" he asked the TARDIS. "It's been centuries since the last time I visited."

***

Groaning, the Doctor picked himself up off the floor as the TARDIS landed. Preferably somewhere as far away from Betelgeuse Seven as possible. He shook his head, trying to clear it, before glancing around the smoke-filled room.

"Galactic Sidereal Year 03758," he said, flinching as something on the far side of the room exploded in a shower of sparks. He just hoped whatever it was wasn't too important. "Of all the times to visit, it _had_ to be Galactic Sidereal Year 03758. Right in the middle of the Great Collapsing Hrung Disaster."

Then he grinned. "Though at least now I know for a fact how to pronounce Hrung properly."

Ignoring the various bits and pieces of the TARDIS that were still smoking, the Doctor cracked his knuckles. "Now, time to see where we are," he said, making his way over to the console. His smile disappeared instantly as he glanced at the screen. Narrowing his eyes, he looked suspiciously around him.

"No, no, no," he protested, stomping his foot slightly for emphasis. "Even I realize this would be a very bad idea. We're going to leave right now before anyone notices that we're here."

The lights in the console room dimmed for a moment before coming back at full strength. The Doctor shook his head. "Don't even start," he repeated firmly. "We're leaving, and that's final."

He grabbed the nearest lever and pulled it, bracing himself for the TARDIS to dematerialize. Ten seconds later, he was still waiting.

"Or not."

***

The Brigadier raised an eyebrow. "You're the Doctor?" he repeated skeptically.

"Yep." The Doctor shuffled his feet for a moment. Then he stopped, remembering a comment Donna had made once about that habit making him look like a schoolboy who knew he was in trouble. "The Doctor. That's me. By the way, Brigadier, I must admit that it's never seemed right seeing you with the mustache. I'm glad you'll decide to grow it back before you retire."

Reaching up to rub his temples, the Brigadier sighed. "Yes, you're the Doctor," he said, no longer sounding uncertain. "You've regenerated, I see."

The Doctor grinned. "Oh, a half dozen times or so since the last time you saw me."

A surprised look appeared on the Brigadier's face, mixed in with a hint of worry. "That many?" he asked. "What about Miss Smith?"

"Sarah Jane?" The Doctor blinked once or twice before he realized what the Brigadier was asking. "Oh, she's fine. Still out there traveling with an earlier me. She'll find her way home eventually."

He paused for a moment.

"By the way," he said slowly, "it might be better if you don't mention seeing me the next time you see me. Any of me, actually."

The Brigadier started to say something, but he apparently thought better of it at the last moment and simply shook his head. "Yes, quite. Tell me, Doctor, why exactly are you here?"

Sheepishly, the Doctor shuffled his feet again. "I'm sort of between traveling companions at the moment," he said, keeping his voice light, "and the TARDIS seems to think that I need a change. So, since I knew that I left UNIT in a bit of a bind when I disappeared with Sarah Jane, I thought that I'd see if you needed a new scientific advisor. Temporarily, at least."

For several seconds, the Brigadier didn't say anything. Then, reluctantly, he nodded. "I suppose we could use your expertise for a while, until we find someone permanent. There have been a few times when it would have made things easier."

The Doctor clapped his hands together. "Fantastic," he said, his face lighting up. "In that case, we should probably do something about the Judoon spaceship that's in orbit before they start transporting buildings to the moon or something."

***

Shaking his head as he walked down the hallway, the Doctor looked down at the small Rhadwemiud power source he was holding in his hand. He wasn't entirely certain that Earth was far enough along technologically to be using the device, but he supposed it was mostly harmless as long as he was the one finding a way to make it compatible with human technology. If nothing else, he knew what he was doing. Somewhat, at least.

Grinning, the Doctor walked into the lab that he had moved the TARDIS into three days earlier. Then he stopped dead in his tracks. Mike Yates was standing in the middle of the room, his hands behind his back. "Captain Yates?" he asked, surprised.

Mike stood up even straighter as he turned his attention away from the mess of wires and tubing on the table next to him. "It's sergeant, actually," Mike said with a weak smile. "Actions always have consequences, Doctor, no matter the mitigating factors."

The Doctor felt his own smile fade somewhat. "Yes, they do."

They stood there a moment, staring at each other silently.

"I didn't realize you were back with UNIT," the Doctor said slowly. "After what happened, I assumed . . ."

Mike shrugged, an embarrassed look on his face. "There was an incident with the Master late last year, after you left. The higher ups decided that my actions deserved some sort of reward, so here I am." He paused, hesitating a moment. "I'm not exactly the most popular person at HQ right now, but I thought I should at least pay you a visit. I heard about what happened on Metebelis III."

The Doctor shook his head. "That was lifetimes ago," he said, gesturing toward a nearby chair and motioning for Mike to take a seat. "Water under the bridge and all that. Now, what were you saying about the Master being back on Earth? The Brigadier forgot to mention that fact, so I guess you get the chance to tell me what happened."

***

Benton put his head though the door to the Doctor's lab, a concerned expression on his face. "Doctor?" he asked. "What are you working on right now?"

The Doctor looked up from the cylinder he was fiddling with. "I'm trying to find a way to get the Rhadwemiud power crystal to work with the metals UNIT recovered after the attempted invasion by the Ghaiju several years ago."

"How's that invisibility shield you've been working on coming along? The one that the Brigadier ordered you to stop wasting resources on?"

"Sergeant, I'm surprised," the Doctor said, theatrically putting his hand over his left heart. "Like you just said, the Brigadier told me to stop working on it."

Benton didn't even blink. He simply stood there, staring expectantly at the Doctor.

The Doctor raised an eyebrow. "It's going fairly well," he said slowly. "It works for fives minutes or so before it . . . explodes is a strong word. Give me a second, and I'm sure I'll be able to think of one that fits better."

"No, that's fine," Benton said, holding up his hand. "I think that explodes probably describes it fairly well."

The Doctor shrugged and started to turn back toward the device he was working on. Then he paused. "Why do you ask?"

Benton cleared his throat. "There's someone here from Cardiff, asking questions about you. Well, about Dr. John Smith, actually."

"Cardiff?"

Frowning, Benton glanced behind him as if he was making certain no one was there. "There's an organization with a branch there that the Brigadier has known about for some time. He never mentioned it to you, but they were very interested in getting their hands on you when you first started working for us."

The Doctor raised an eyebrow. "Huh," he said. "I always wondered why Torchwood never grabbed me during my tenure as UNIT's scientific advisor."

A startled look appeared on Benton's face.

Waving his hand at the sergeant, the Doctor put down the cylinder. "How much time do I have before the Brigadier's guest makes it to my door?"

***

Captain Jack Harkness frowned as he stuck his head through the door and looked around the empty room. "There's nobody here," he said, glancing back at the Brigadier. "I didn't know you had a sense of humor."

"I don't," the Brigadier replied dryly. "As I told you, Captain Harkness, our current scientific advisor is only a temporary replacement until we find someone more suited for the position. He isn't always at HQ."

Shaking his head, Jack turned away from the doorway. "You wouldn't be lying to me, would you?" he asked, casually reaching behind Benton as he spoke to the Brigadier. Judging by the startled look on the sergeant's face, Jack's hand had found its intended target.

"I'd be careful about making accusations, Captain," the Brigadier replied coolly, "and if you don't keep your hands where we can see them, I iwill/i shoot you this time."

Jack laughed as he started back in the direction they had come from. "Is that a promise?"

As the sound of their voices disappeared down the corridor, the Doctor flipped the switch on his makeshift invisibility cloak. A few sparks flew from it as the device shut itself off, but for once there wasn't a significant amount of smoke.

"I'm sorry, Jack," he said softly. "It's just not the right time."

Then the device on the table burst into flames.

***

The Doctor didn't look up when he heard someone knocking on the door to his lab. "Just a second!" he called out, his attention focused on the plant pod that he was poking with a needle. A green tendril darted out to slap his hand, and he let out a surprised yelp and quickly moved his hand away.

The person knocked again.

Rolling his eyes, the Doctor finally looked up. "I said just a . . ." He trailed off, his eyes wide.

Jo smiled hesitantly at him from where she was standing in the doorway. "Doctor?" she asked. "Is that you?"

"Jo?" Laughing, the Doctor practically dashed to the door. He lifted her off the ground, swinging her around him before pulling her close for a tight hug. "What on earth are you doing here?"

He put her back down, giving her the chance to look at him. She stepped back for a moment, her gaze moving over him before finally stopping on his eyes. Recognition darted across her face. "It is you," she said slowly. "I thought . . . well, Mike always did like to joke."

The Doctor grinned at her. "Tell me, Mrs. Jones, what is a happily married woman such as yourself doing back at UNIT?"

Jo smiled. "We're traveling to Wales," she explained. "Cliff has a brother who works as a tailor there, and he's getting married next week."

"That explains why you're not in South America," the Doctor said, raising an eyebrow. "What it doesn't explain is why you're here in UNIT HQ."

Her eyes moved pointedly toward the plant he had been examining when she came in. A crack had appeared in the pod, revealing a row of teeth. It made a hissing sound and snapped at the Doctor's still out of reach hand.

The Doctor let his gaze drift between her and the plant. "Ah," he said slowly. "I suppose we should warn the Brigadier that there's a possible invasion in progress."

center***/center

"For the last time," the Doctor protested, waving Harry Sullivan away from him, "it's nothing. If you'll let me go back to the TARDIS, I'll be able to heal the burn in less than five seconds."

Harry shot the Doctor a skeptical look. "That's what you told us after the incident with the dragon," he pointed out. "I still have scars."

The Doctor rolled his eyes. "You do realize that it wasn't an actual dragon?"

"It had red scales and breathed flames," Harry said matter-of-factly. "It was close enough for me."

Shaking his head, the Doctor took a few steps toward the door. Harry quickly stepped in front of him. "Since you're in the sickbay, you could at least let me take a look at it." His eyes twinkled a bit. "Unless you're still worried that I'm only qualified to work on sailors?"

The Doctor chuckled. "I had almost forgotten saying that," he admitted. "It's been centuries."

"It's been considerably less time for me," Harry said, not moving. "Will you at least tell me what happened to you hand?"

The Doctor purposely kept his hand out of Harry's reach. "I've been working on a project for the Brigadier between invasions," he replied with a shrug. "Sometimes it explodes."

Harry nodded. "Yes, I heard about that. You're working on the power system that they eventually plan on using in _The Intrepid_, correct?"

"I suppose so," the Doctor replied, glancing longingly toward the open door. Then he paused. "Wait, _The Intrepid_?"

"The name's not set in stone, of course," Harry added quickly, "since it will probably be decades before it's actually finished. Personally, I thought _The Gallant_ would be a better name. Or possibly_ The Dauntless_."

As comprehension dawned on him, the Doctor frowned. "Or _The Valiant_," he muttered, pushing past a protesting Harry.

"Sorry!" the Doctor called back over his shoulder. "I need to let the Brigadier know that I won't be staying much longer."

***

"You're my replacement?" the Doctor said, openly gaping. "The Brigadier told me that he'd found someone, but I didn't expect it to be _you_."

Liz Shaw quirked an eyebrow. "Is it that difficult to believe?" she asked. "Believe it or not, Doctor, I am a scientist."

The Doctor stared at her for a moment, not saying a word. Then his face broke into a smile. "Yes, you are. A very good one, even if I was too blind to see it."

"You're admitting that you were wrong?" Liz said, her mouth twitching. "I never thought I'd live to see the day, Doctor."

He held out his hand.

Startled, Liz stared at him for a moment. Then she reached out her own hand to shake his.

"I couldn't have chosen a better replacement myself," the Doctor said, not a hint of sarcasm in his voice. "You're going to do a fine job, Dr. Shaw."

She smiled. "The Brigadier told me to remind you that there's paperwork for you to fill out before you leave, and if you even think about disappearing in the TARDIS before doing it then he'll be the cause of your next regeneration."

The Doctor's smile faded somewhat.

***

The Doctor moved his gaze from the towering stack of paperwork sitting in front of him to Harry's face. "Really?" he asked, a nervous look on his face. "Aberdeen, you say?"

Harry Sullivan nodded. "I must admit, Doctor, Sarah seemed rather upset with you on the phone."

The Doctor quickly stood up, not even noticing the huge number of papers that went crashing to the floor. "And you said the Brigadier sent Benton to pick her up this morning?"

Nodding, Harry glanced at his watch. "They should be back any time now."

"Harry, could you do me a favor?" the Doctor asked, glancing at the door. "Just a small one."

Harry sighed. "You're about to make a dash for the TARDIS, aren't you?" he said, shaking his head. "And you want me to explain to the Brigadier why all of this paperwork was left behind for him to fill out. Again."

The Doctor grinned at him. "Just tell him that it would probably destroy the planet if Sarah Jane saw me."

Then he made a break for the door. If nothing else, he knew how to make an escape.


End file.
